Elastic fluid compressor



May 17, 1932. cs. E. T. E'YSTON ELASTIC FLUID COMPRESSOR 3 Sheets-Sheet 1 Filed Sept. 22, 1928 May 1 7, 1932. G. E. T. EYSTON ELASTIC FLUID COMPRESSOR Filed Sept. 22, 1928 5 Sheets-Sheet 2 y 1932- G. E. T; EYSTON 1,858,921

ELASTIC FLUID COMPRESSOB Filed Sept. 22, 1928 s sheets-sheet s I jackets;

Patented May 17, 1932 GEORGE. EDWARD THOIVIAS EYSTON, OF LONDON, ENGLAND, ASSIGNOR TO POWER-PLUS (1927) LIMITED, OF LONDON, ENG-LAND, A CORPORATION OF GREAT BRITAIN ELASTIC FLUID COMPRESSOR.

Application filed September 22, 1928, Serial No. 307,711, and in Great Britain November 26, 1 927.

This invention comprises improvements in and connected with elastic fluid compressors and has for its principal object to improve the efliciency of air or gas compressors and also to 5 improve the construction and working of radial cylinder compressors or piston blowers as they are sometimes called.

The term compressors is intended to mean not only compressors as such, but also other apparatus in which compression of a. gaseous medium takes place, for example, the cylinders of internal combustion engines.

In the art of compressing gases, it is known theory that the work performed in producing a given degree of compression can be reduced it heat is abstractedtrom the air or gas during the compression stroke. The same benefit is not derived if the heat abstraction takes place after the work of compression is completed, as for example, by cooling the delivery of the compressor. In attempts to effect cooling during the work of compression, the compressor cylinders have been fitted externally with heat exchange devices and with cooling in all such cases, however, the heat abstraction is poor, partly by reason of the rapidly diminishing cooling area presented as a compression stroke is completed, and partly by reason of the fact that the com pressed gases are in a more or less stagnant or dead'condition so that a gaseous film exists between the metal walls and the body of gas to be cooled, which film is a bad conductor of heat and is actually obstructive of a free 33 exchange of heat between the body ofheated compressed gas and the cooled containing metal. walls. Known cooling arrangements may be suitable in some instances, for low rates of compression, but what is required is a compressor adapted for a much higher rate of compression, that is to say, the attainment of a given elevated degree of compression in a very short space of time.

In operating multi-cylinder compressors, it is very important to provide for perfect balance, particularly if a high rate of operation is desired with a minimum expenditure of energy and minimum vibration.

In its broadest aspect, this invention provides for the movement of an elastic fluid over, or bodily in relation to, a cooling device during the period of its compression. Such movement produces disturbance and even turbulence in the body of compressed fluid so that the latter makes active contact with the cooling device and an efiicient heat exchange takes place.

This movement of the fluid over a cooling device during the period of compression may be produced. in any suitable manner. In the case of single cylinder compressors the cooling device may be placed in the head of the cylinder and arrangement made for causing a tortuous or lateral movement of the fluid on entry into the cylinder or exit therefrom, so that it is caused to swirl in contact with the cooling device.

' In a construction in which two compressor cylinders are opposed and their pistons compress the fluid into a common compression chamber or space, movement of the compressed fluid over a cooling device may be promoted by causing the pistons to have different movement or instant rates of movement or different strokes or phasing.

The invention is most advantageously carried out in a multi-cylinder compressor havingthe cylinders radially arranged and communicating at their inner ends with acommon compression chamber wherein is disposed a cooling device which may be part of a water circulation system including jacketed covers for the common compression chamber.

In order toreduce clearance, the inner ends of the pistons may be fashioned so as to fit together when they enter convergently into the central compression chamber of a radial cylinder compressor and so fill the free space of said chamber. In some cases, as the compression space or chamber is partly 0ccupied by the cooling device, the inner ends of the pistons may require to be fashioned to suit the free space as modified by the presence of the cooling device in such space. If the cooling device is formed with radiator fins, heat exchange devices, or parts designed to give an enlarged cooling area, the inner ends of the pistons may have to be further modified, as by providing them with slots or recesses, for the purpose of accommodating any such projecting parts when the pistons arrive at their inward position.

In any of the constructions owing to the cooling device being outstanding in the compression chamber, there will be movement of the compressed fluid in relation to the cooling device, so that the surface of the latter is laved by such body of fluid and an improved co-eflicient of heat transfer and efflcient heat-interchange are accomplished during the compression period and before delivery. Arrangement may also be made in any of the constructions for the fluid to be actively circulated over the cooling device during induction as well as during compression.

In addition, it will generally be advantageous to design the inlet valves, whether automatic or mechanically governed, or the inlet passages, so that the air is rendered already as turbulent as possible during the induction stroke which turbulence will persist during the compression stroke and further assist the cooling.

In application to internal combustion engines, cooling provision of the nature described would have beneficial eflect in some cases in reducing detonation or excessive heating during compression. The cooling device may be arranged in the head of the cylinder and the construction of the piston modified to suit as would be readily understood.

In order further to explain the invention in its practical application, description will now be given of suitable examples of compressors with the aid of the accompanying and more or less diagrammatic drawings in which Figure 1 is a sectional elevation of a multi-radial cylinder compressor in accordance with these improvements.

Figure 2 is a sectional plan of Figure 1.

Figure 3 is a sectional elevation of a construction comprising two opposed cylinders and illustrating a sleeve form of valve mechanism.

Figure 4 is a sectional part plan ofFigure 3.

Figure 5 is a fragmentary view illustrating certain modifications hereinafter referred to.

Figure 6 is a sectional elevation of a further form of opposed cylinder compressor.

Figure 7 is an irregular cross-section of gle cylinder compressor.

The construction shown in Figures 1 and 2 comprises, in general, a compressor body A, base B and a motor C. In the compressor body, a number of radial cylinders a are uni- 1 formly spaced around a more or less circular compression chamber 2) which is common to all the cylinders. The walls of the cylinders a andthe end covers or heads 0 of the compression chamber are water jacketed as at (Z. The motor 0 for driving the compressor may impart motion to the pistons g of the cylinders a by gearing so that all pistons move together on their inward and outward strokes and thus preserve balance. The gearing may, for example, comprise a central spur gear it on the motor spindle i and outer gears on crank spindles Z, the cranks m driving respective pistons g. The inner ends of the pistons or piston heads extend into the common compression chamber 6 at the end of each inward stroke as will be apparent and such ends are of conical or wedge formation in plan as shown at n so as to fit together and fill the free space in the compression cham ber in that position. The end covers 0 of the compression chamber are fitted with inlet valves 0 and outlet valves 10, preferably each to a number equal to the number of cylinders and in pairs radially aligned with the cylinders in plan. These valves may be of the automatic variety or positively operated in any suitable manner.

For cooling or heat-abstraction purposes in accordance with the invention, an annular water-tube device as shown at g is suitable, which extends through the compression cham ber b from one head or cover 0 to the other head or cover and has its annular space in communication with the cooling jacket spaces (Z aforesaid. This water tube device is adapted for withstanding the pressures which are developed in the compression chamber 6 and, if desired, the tube may be provided with extended surfaces to increase the cooling area as will be hereinafter described with reference to Figure 5.

The compressor body A is mounted on legs 6 above the bottom plate of the base B so as to allow free passage of air or gas to the inlet valves 0, the fluid entering through the strainers r in the outer cover 8 of the compressor, and the motor C may be mounted on legs it above the compressor body so that delivery of compressed air or gas from the apparatus may take place through a pipe at v. This pipe leads from an annular chamber w formed in the top cover 0 and constituting a common outlet for all the compressor cylinders.

The water-tube device Q is made annular to allow of passage of the motor spindle z and the latter and the crank spindles Z are mounted in bearings in the compressor body A and stepped into hearings in the base B.

In the operation of the compressor, all pistons 9 move inwardly during the compressor stroke and compress air or gas into the common chamber 6. The streams of air or gas impelled by the various pistons converge and also impinge upon the cooling device 9 within the compression chamber.

There is always a certain amount of slight irregularity in operation between a number of pistons such as are used in this construction and thus movement, disturbance or turbulence of the air or gas in relation to the cooling device takes place and this effects an active cooling during compression; possibly also a certain state of disturbance has already been imparted to the air owing to its motion in travelling through the inlet valves into the common compression chamber b.

The movement, disturbance or turbulence of the air or gas can be increased by modifying the strokes of pistons in opposed cylinders as by varying the setting of the cranks m aforesaid. This, while not afiecting the balance, may be adapted for producing a pulsating flow between cylinders of a pair, the pulsations passing over the cooling device q outstanding in the compression chamber as well as over the water-cooled walls of the chamber.

In the modified form of compressor illustrated by Figures 3 and 4;, there are two cylinders 1, 1, disposed directly opposite to each other on either side of a central compression chamber or space 2 and fitted with respective pistons 1 1. The cooling tube 3 extends from top to bottom of the common compression chamber 2 and the pistons fit around the cooling tube at the inner end of their stroke and fill the compression chamber. In this construction the cooling tube 8, is utilized for the mounting of a rotary valve or valves for controlling the inlet and exhaust. As shown, the cooling tube device 3 may be of the same general construction as in Figures 1 and 2, but it is formed withoppositely disposed ports l and 5 in pairs respectively constituting inlet and outlet ports to and from the compression chamber 2. For controlling these ports a valve 6 of the rotary hollow cylindrical type may be revolubly mounted within the cooling tube and connected between the motor spindle i and the central gear 7 employed for driving outer gears 8 on crank spindles 9 in driving connection with the piston rods as in Figures 1 and 2.

The valve 6 has pairs of ports 10, 11, and the construction of the valve is such that at one period during a revolution the ports 10 coincide with the ports 1 of the cooling tube 3 for admitting air to the compressor cylinders under suction by the pistons, while at another period those ports are closed and the other ports 11 come into coincidence with the other ports 5 of the cooling tube to allow delivery of compressed air axially of the valve to a central delivery 12. As will be seen the compressed air is not only cooled in passing over the exterior of the cooling tube 3 during compression but further cooling is effected in passing through the ports and interior of r the cooling tube as will be readily understood.

Figure 5 illustrates how the cooling device may be providedwith extended surfaces to increase the cooling area as aforesaid. The cooling tube, which is shown at 13 and may be of the same general construction as that seen in Figures 3 and 4c, mayfor example, be formed externally with fins or like heat-exchange parts 1 1. Such fins or the like, if used, will constitute projections on the cooling tube and, therefore, the ends of the pistons such as 15 will require to be recessed as indicated at '16 to receive such projections. In any construction, of course, the ends of the pistons must be shaped so as not to foul the cooling tube when the piston heads come to the end of each inward stroke. Figure 5 further shows that the covers or sides of the compression chamber may be formed with similar fin devices, such as 17, and these may be adapted to project well-into the compression chamber. With any such devices on the covers or sides of the compression chamber, the ends of the pistons, as before would be fashioned to suit the configuration thereof.

In the opposed cylinder construction shown in Figures 6 to 8, pistons 18, 19 are arranged in respective cylinders 20, 21 of a stepped cylinder construction and advantage is taken of the step or shoulder between the cylinders for the mounting of the inlet and delivery valve fitting 22. The pistons are driven by a crankshaft 23, the smaller upper piston through outside connecting rods 24 and cross-head rod 25 and the larger lower piston through an internal connecting rod 26 and gudgeon pin 27 The upper piston member 18 has parts cut away at 28 for sake of lightness and the cross-head rod 25 moves in slots in the cylinder wall at 29. The cooling tube 30 is situated at the junction of the upper and lower cylinders. The latter is also jacketed for cooling purposes, the upper and lower jackets being connected by pipe 31. The tube 30 is suitably connected to the cylinder jacket space by ports 30 Figure 8, and it may also have connection with the pipe 31. It is recessed at the parts 30 to allow mounting of the valve fitting 22 and it may be assembled by casting the cylinders with the tube in position in the moulds for which purpose the tube is conveniently made in halves and when the upper and lower cylinders are assembled, the halves are packed together along the joint 30 The inlet and exhaust valves 32, 83 respectively are ct disk or plate form and automatically acting. Entry to the inlet valves is direct from the atmosphere through a ring of holes 34 in the valve fitting 22. Delivery is also through a ring of holes 35, the compressed fluid passing to an annular duct 36 with outlet connection 37. The cranks for driving the pistons are 180, out of step with each other and in order to ensure proper balance the throw of the respective cranks is made different. The crank throw depends on the weight of the pistons and connecting rods and if the small top piston 18 and its connecting rod weigh half as much as the lower piston and its connecting rod, the stroke of the small piston should be twice the stroke of the larger one. In this construction also, owing to the arrangement of the valves and pistons, active circulation of air over the central cooling pipe is obtained during both induction and compression. During compression, the dif ference in bore is mainly responsible for causing circulation. In this construction also, the cooling tube 30 may be provided with extended cooling surface formations 14 fitting similar formations of the pistons 18, 19.

The modification illustrated by Figure 9 is a simple form which does not dictate a special construction of pump but can be embodied in existing designs of compressor with little alteration. The induction and delivery valves are shown at 38 and 89 respectively and the cooling device 40 is an annular chamber inserted or formed in the head of the cylinder 41 and having connection with the cooling jacket space 42 of the latter. There is a partition 43 across the central space of the cooling device and this is formed with one or more ports 44. The piston 45 is constructed to conform with the shape of the cooling device and as will be seen, the entry port 44, being displaced laterally with respect to the induction valve 38, the air is caused to partake of a tortuous or lateral movement in entering the cylinder, so that turbulence is produced with consequent favourable movement of the fluid in contact with the cooling device. If more than one entry port 44 be used, they may all be displaced with reference to the inlet valve for the purpose stated as will be readily understood. The projections 46 on the interior of the cooling device are to facilitate or improve the circulation of cooling liquid. In applying this construction in connection with existing compressors, all that is necessary, apart from fitting the cooling device, is to provide a new piston of the form stated.

I claim:

1. In an elastic fluid compressor, the combination of a compression cylinder and piston, a cooling device in said compression cylinder, and means for causing the fluid compressed to move bodily over the surface of such cooling device during the operation of the piston.

2. In an elastic fluid compressor, the combination of a plurality of compression cylinders with compression space common to said cylinders, pistons operative in said cylinders, and a cooling device associated with said compression space so that the fluid compressed moves bodily over the surface there of during compression.

3. In elastic fluid compressors of the nature claimed in claim 1, the construction according to which the cooling device is connected in the circuit of the cyllnder cooling system.

4. In an elastic fluid compressor, the combination of a compression chamber, a plurality of compression cylinders arranged radially with respect to said compression chamber, a cooling device disposed centrally in said compression chamber, and compressioncylinder pistons formed to fit together and about the cooling device at the inner end of their stroke substantially as set forth.

5. In an elastic fluid compressor, the combination of a compression cylinder, cooling means in said cylinder and provided with e tended cooling surface formations,andacompression piston for said cylinder having formations corresponding with said formations on the cooling means substantially as set forth.

6. In an elastic fluid compressor, the combination of a plurality of compression cylinders of difierent diameters, pistons arranged in the respective cylinders, a cooling device arranged at the junction of the cylinders, inlet and exhaust valves fitted at the step between the cylinders and means for imparting different strokes to the pistons.

7. In an elastic fluid compressor in accordance with claim 6, an inlet and exhaust valve fitting for the cylinders comprising disk valves of annular form substantially as set forth.

8. In an elastic fluid compressor, the combination of a plurality of compression cylinders of different diameters, opposed pistons arranged in the respective cylinders. means for driving the pistons consisting of cranks of different throw angularly spaced at 180 from each other. automatic inlet and exhaust valves arranged at the step between the cylinders, and a cooling device arranged at the junction of the cylinders substantially as set forth.

GEORGE EDWARD THOMAS EYSTON. 

